Observation: NWAC Observer

All Observations

Basic Information

Observation Details

Observation Date:
January 21, 2023
Submitted:
January 21, 2023
Observer:
NWAC Observer - Brooke Maushund & Katie Warren
Zone or Region:
East Central
Location:
Turnpike Creek Drainage (SE-E-NE & SW-W-NW // 3100'-6300')

Signs of Unstable Snow

Recent Avalanches? 
Yes
Cracking? 
Isolated
Collapsing? 
None Experienced

Media/Attachments

Snow profile from 01/21/2023 on E aspect, 6000' in the Turn Pike Creek Drainage
Ridgeline cornice development. Wind slabs were found on both E & W sides of ridge.
Small old wild slab ATL E facing slope @6000'
Blowing snow at ridgeline.
Wind pressed snow made for variable skinning conditions.
While the visibility made the scale of the Turnpike Creek avalanche hard to capture on camera, it reached from behind Katie, seen here, to the farthest slope visible in this photo
We travelled carefully to avoid the hazardous hangfire above the crown. The upper layers of the hangfire had creeped over lower layers, as seen here.
Observing the 1/4 buried SH
Shovel tilt test on the 1/18 near surface facet layer

Advanced Information

Weather Summary

Cloud Cover:
Overcast
Wind:
Strong , W
New/Recent Snowfall:
HN 11cm

Skies were blue (CLR) and winds calm when we left our snowmobiles to begin our skin. Cloud cover, wind, and precipitation increased throughout the day, skies becoming completely socked in (OVC), winds increasing to strong out of the W, and precipitation at S1+ by 15:00.

Avalanche Observations

 #  Date Location Size Type Bed Sfc Depth Trigger Photos Details
1 Jan 19, 2023
() 		Teanaway Area - The Funnel
W 5800ft 		D2
R2 		HS-Hard Slab O-Old Snow N-Natural
Avalanche debris in the middle stretch of the feature.
Report
1 Jan 14, 2023
() 		Turnpike Creek
E 6200ft 		D3
R3 		SS-Soft Slab O-Old Snow 2ft N-Natural
Photo: Rob Pollard
Photo: Rob Polard
Crown Profile of Turnpike Creek Avalanche. Failed on the 1/4 layer of buried surface hoar.
Report
Teanaway Area - The Funnel
Turnpike Creek

We observed an older large D3 R3 SS avalanche from earlier this past week on an easterly aspect in Turnpike Creek running on the 1/4 buried surface hoar layer NTL with a crown more than .5mi long. We also observed an old D2 R2 HS slide from >48hrs ago on a westerly aspect in a terrain trap at similar elevations. See linked occurrences for more information.

Snowpack Observations

We travelled carefully into the Turnpike Creek Drainage, avoiding the large amount of hang fire, to investigate the recent large slide. We confirmed that the large D3 Turnpike Creek avalanche did run on the 1/4 SH, likely running during the MLK storm. In a quick profile at the crown, we confirmed the presence of the surface hoar as the slide surface. On a similar slope in the same drainage, we observed 11cm of new snow on top of a new thin layer of near surface facets on the 1/18 interface, with the 1/4 buried SH 78cm down into the snowpack. On this 1/18 near surface facet layer, we were able to get a sudden planar failure with easy force on a shovel tilt test. Our other test results were ECTX, and we observed that while the 1/4 SH layer is present, it is starting to round.

Avalanche Problems

Problem Location Distribution Sensitivity Size Comments
Wind Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Comments: We observed wind slabs on both the E and W side of ridges and on the upper reaches of NTL, indicating that shifting winds have blown snow in both directions. While the wind slabs were stubborn, they were up to 16cm thick, and winds were increasing to strong with more snow falling and available for transport as we departed from the drainage. Small to medium-sized cornices lined the ridge.
Persistent Slab
Isolated
Specific
Widespread
Unreactive
Stubborn
Reactive
Touchy
D1
D1.5
D2
D2.5
D3
D3.5
D4
D4.5
D5
 Weak Layer(s): Jan 4, 2023 (SH)
Comments: About one week ago a D3 slide ran on this layer. However, similar aspect & elevation slopes in the same drainage failed to have similar slides. This speaks to the uncertainty in the distribution and reactivity of this problem.
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